Vibrator conveyor system of this type is known in several versions from U.S. Pat. No. 3,048,260, Willis. The means for the reciprocating or oscillating plate include a number of oscillating armature motors, which in common with laminated spring packets individually associated with each oscillating armature motor are combined into drive units. Each of these drive units has an approximately rectangular base plate having the stator, and an auxiliary reciprocating plate having the armature screwed onto it, and braced against the base plate via the laminated spring packets. With their base plates and auxiliary reciprocating plates, the component units are each secured by means of central fastening bolts to a common base frame or to the common reciprocating plate of the vibrator conveyor system. For greater stability, especially when the system is formed as a circular conveyor, the base frame is a cast part having an additional inertial mass.
Since the elongated spring elements on the individual drive units have a predetermined, fixed three-dimensional orientation with respect to their pole surfaces, the result, particularly in the case of a circular conveyor, is a complicated arrangement, with skewed transverse axes of the units on the base frame and the common reciprocating plate. To avoid unfavorable vibration and hence so-called dead zones on the common reciprocating plate, the individual units must be adjusted exactly in terms of their three-dimensional position following installation, which is complicated and labor-intensive. Because of the fundamentally unfavorable drive relationships of the common reciprocating plate, such a vibrator conveyor system also has limited efficiency.
A more favorable arrangement of the spring elements is found in a drive assembly known from German Patent Disclosure Document DE-OS No. 20 51 573, intended for generating simultaneous up-and-down and rotational movements, in particular for screw conveyors, having two parts movable relative to one another; these two parts and the connecting elements forming the spring elements of these parts are combined into a plastic body. This plastic body is substantially cup-shaped with a perforated cup wall, the annular rim of which is formed by one of the two parts, the perforated cup wall by the connecting or spring elements, and the cup bottom by the other of the two parts. Aside from the fact that the one-piece plastic body must be made from costly and complicated molds, the spring forces that can be generated in this way are limited because of the elastic properties of the plastics available. Also, the plastic body must be accommodated in a cup-shaped sheath connected with the chassis. A single coaxial oscillating armature motor is used as the drive, housed in the plastic body and exerting a force coaxial to the axis of rotation upon the armature connected to the flat part of the plastic body. It is impossible to embody a linear conveyor system in this way.